1. Field of the Invention
The present invention generally relates to a disc cartridge for use in an information read/write apparatus and, more particularly, to the disc cartridge particularly suited for use in an information read/write apparatus of a type employing a plurality of recording and/or reproducing heads.
2. Description of the Prior Art
As is well known to those skilled in the art, an information carrier disc such as, for example, an optical disc, is accommodated within a generally rectangular disc cartridge not only for protecting the information carrier disc from being contaminated by finger prints and/or dust, but also for improving an operativeness of the information read/write apparatus.
For example, Japanese Laid-open Patent Publication No. 60-98578, published Jun. 1, 1985, discloses a generally rectangular flat disc cartridge accommodating therein a round information carrier disc. This prior art disc cartridge is so designed and so structured that the user of the apparatus need not remove the information carrier disc from the disc cartridge in readiness for a loading thereof into the information read/write apparatus, remove the empty disc cartridge after the loading and insert the empty disc cartridge in readiness for a recovery of the information carrier disc from the information read/write apparatus after an information recording or reading has been completed.
The prior art disc cartridge referred to above has a width in a direction perpendicular to the direction of insertion or removal of the disc cartridge into or from the information read/write apparatus, which is somewhat smaller than the length thereof in a direction perpendicular to the widthwise direction thereby to avoid an incorrect insertion of the disc cartridge into the information read/write apparatus. This disc cartridge comprises front and rear casings defined by splitting the disc cartridge across the width thereof at a position generally intermediate of the length thereof, the front casing being adapted to move a first predetermined distance relative to the rear casing in the lengthwise direction of the disc cartridge. Generally elongate stationary and movable support members are provided on each side of the information carrier disc within the disc cartridge and along each of opposite side walls thereof. Only the movable support members on the respective sides of the information carrier disc are movable a second predetermined distance, which is half the first predetermined distance, in a direction conforming to the lengthwise direction of the disc cartridge.
The elongate movable support members while the front and rear casings are closed together cooperate to support the information carrier disc in a fixed position within the disc cartridge. However, when the front and rear casings are separated from each other by moving the front casing relative to the rear casing over the first predetermined distance leaving an access opening therebetween, the elongate movable support members are moved the second predetermined distance relative to the stationary support members within the rear casing, allowing the information carrier disc in position ready to be rotated for an information reading or writing operation.
When in use in the information read/write apparatus, the disc cartridge in a closed position is inserted into or ejected from a cartridge receiving mouth of the apparatus. The information read/write apparatus must have a cartridge loading and unloading mechanism installed therein. The cartridge loading and unloading mechanism includes two parallel rows of paired roller elements grouped for each of the front and rear casings. Although first and second groups of the paired roller elements are driven at the same speed up until the disc cartridge in the closed position is completely inserted into a cartridge receiving mouth in the apparatus, the first group of the paired roller elements are held still while the second group of the paired roller elements are allowed to continue rotation so that the rear casing within the cartridge receiving mouth can further be moved relative to the front casing to form the access opening between the front and rear casings with the disc cartridge consequently held in an open position.
The access opening between the front and rear casings is of a size corresponding to a turntable or a chuck assembly by which the information carrier disc can be clamped for rotation together with a motor-coupled spindle. The movement of the paired movable support members over the second predetermined distance, i.e., half the first predetermined distance, is necessary to bring a center hole of the information carrier disc into alignment with the longitudinal axis of the motor-coupled spindle and at a position generally exactly intermediate of the spacing of the access opening.
As discussed above, the prior art disc cartridge is complicated in structure employing such a substantial number of component parts as to adversely affect the reliability of operation of the disc cartridge and, at the same time, requires the information read/write apparatus to be equipped with a complicated cartridge loading and unloading mechanism.